Problem: In his physics class, William took 4 exams. His scores were 93, 89, 87, and 95. What was his average score on the exams?
Explanation: The average is the sum of his scores divided by the number of scores. There are 4 scores and their sum is $93 + 89 + 87 + 95 = 364$ His average score is $364 \div 4 = 91$.